DE2502273A1 - METHOD AND DEVICE FOR PRODUCING POLYMER FIBRILLES - Google Patents

Description

PATENT ANWALTSBÜRC TlEDTKE - Bühling -

TEL. (089) 539653-56 TELEX: 524845 tipat CABLE ADDRESS: Germaniapatent Munich

8000 Munich 2

Bavariaring 4

P.O. Box 202403 21 JAN. 1975 B 6409 - case Q / P 26 728

IMPERIAL CHEMICAL INDUSTRIES LIMITED London, United Kingdom

Method and device for the production of polymer fibrils

Addendum to patent (patent application P 23 48 485.7)

The invention relates to the production of fine fibers or fibrils of thermoplastic polymers and in particular to fibrils of crystallizable polymers in which the polymer chains are oriented and includes an improvement or modification of the process according to the main patent ... (patent application P 23 48 485.7 dated September 26, 1973).

The main patent relates to a method for producing fibrils (as defined below) from one thermoplastic polymers, in which a dispersion of molten or heat softened particles of the Polymers in a liquid medium that is a non-solvent

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for the polymer under the prevailing conditions, through one or more openings (the one defined below Art) - is pressed, whereby the polymer particles are stretched or elongated into a fibril shape.

In this context, the term "fibrils" is intended to mean short fibers which, for example, have a diameter of <50 <µm, preferably < 10 / am and aspect ratios of> 20 and preferably > 100 have.

The opening or openings used in this process can be nozzles, preferably circular Cross-section or slots, provided that the smallest dimension (i.e. the diameter of the nozzle or the Width of the gap or slot) is small enough to create a hydrodynamic area that is suitable for deformation the particles make elongated fibrils. Generally, in the case of circular ones, the diameter will be Openings in the range of 0.2 to 2.0 mm, but in the case of a slot the width will generally generally be Range from 0.1 to 3 mm.

The term "slot" or "gap" is intended to mean a gap between two spaced apart, essentially include parallel surfaces. For example, two circular plates or disks can be placed opposite one another.

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standing apart to form a narrow gap or slit. A dispersion can then Gap are fed through a feed line penetrating the center of one plate in such a way that they are in one Series of radial paths is pressed through the gap. It is also possible to reduce the dispersion by a number of To drive gaps or slits through it.

Now that form of this method has been modified in which the dispersion through a slot or Gap is driven.

In the method according to the invention for producing fibrils of a thermoplastic polymer is a Dispersion of melted or heat softened particles of the polymer in a liquid medium that is under the prevailing conditions a non-solvent for the polymer is, by an elongated, slit-like Driven orifice which has such a geometry that dispersion is caused during its passage to go through at least one substantial change of direction.

It should be noted that the dispersion comprises only polymer particles on entry into the opening, while a high proportion of polymer fibrils is dispersed in the liquid medium upon exit from the opening. Society-

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_t_

In the context of the present description, the term dispersion is technically used for all polymer dispersions, regardless of whether the polymer is in the form of particles, fibrils, or mixtures of both.

Preferably, the opening has such a geometry that the dispersion during its passage through the Opening undergoes path changes of about 90 at least once.

The width of the gap or slot is generally between 0.1 mm and 3 mm and preferably between 0.5 and 2 mm, so that the required "hydrodynamic" or fluid dynamic Area is generated by or in the liquid phase of the dispersion. In the context of this description the term "width" is intended to mean the spatial distance between the boundary walls of the gap or slot.

The required gap-like opening can be provided by any suitable means such as For the sake of simplicity, referred to as a "fibrillator".

A suitable form of fibrillator comprises a pair of rigid members each having a flat surface, wherein the surfaces facing each other to form a gap-like opening [between "each other") spatially

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are spaced apart and one of these elements is provided with a feed line leading to a mouth in the flat surface of the element and through which a polymer dispersion leads to the central area of the opening while each of these surfaces is centered on its periphery through which the dispersion is forced to undergo a substantial change of direction before it comes out of the gap-like one Opening exits.

In a preferred form of fibrillator, the gap-delimiting surfaces comprise the flat end or end faces End faces of two complementary generally cylindrical solid elements (one spanning and one engaging Element), with the engaging element arranged vertically within the overlapping element and is removed from this to form a gap-like opening in the form of an annular step gap and wherein a Feed line with a central opening in the base of the overlapping element is connected in such a way that the dispersion can be forced through the annular step gap or provided with a step annular gap to flow.

It can be seen that the dispersion causes a substantial change in direction as it flows through the ring ST> old when it crosses the edge of the 'ring step.

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In a modified form of the fibrillator described above, the outer surface of the engaging Element and the inner surface of the overarching element with a row. of discrete complementary Steps of increasing or decreasing radius can be conically tapered by corresponding vertical Annular surfaces are connected to form a multi-stage annular gap, which the dispersion during their Forcing passage to several changes of direction.

According to another arrangement, the fixed elements comprise a pair of circular plates which face each other arranged and provided as described with a central feed line, each plate on its The periphery is provided with an attached edge or hem and thus the free space between the edges or hems forms the vertical component of the annular step gap. Each edge or hem can also be divided into a series of ring stages extend downward with increasing radius to form a multi-stage annular gap, as in the case of those described above coordinated fixed elements.

In yet another arrangement, the spaced apart panels are with complementary annular ridges provided, with the grooves in one plate vertical

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Above the ridges in the other are arranged, forming a gap that allows the necessary changes in direction when the dispersion is driven radially through the gap from the central feed line.

It will be appreciated that the dimensions of the two plates or fixed members and the distance between them be chosen in each arrangement so that a gap of the required width is formed. It is common possible to provide the arrangement for a variation of the gap width by relative movement of the two elements.

It should be noted that in all of the above forms of fibrillator it is necessary that the two gap-limiting Elements are rigidly spaced from one another and preferably should allow some allowance for variation their relative position can be provided at least for fine adjustment of the gap width.

This can be accomplished by any suitable passport or location means that detects the output of the gap-like opening not blocked. Preferably the locating means is within the gap-like ones Opening provided at a point before the dispersion undergoes its change of direction, so that any obstruction the flow passing through the locating means

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has minimal effect on the fibrillation process. For example, a Fixation or localization rod fixed in the center of the gap-delimiting surface of an element and in the central one Be anchored feed line of the other element.

In a preferred embodiment, however, the fixation or localization means takes the form of two or three several fixing rods or pegs that reach through an element and are provided with internal threads Holes in the other element engage or are screwed in. The pins are preferably provided with washers, which are clamped between the two elements and thus determine the distance between them. The advantage of this Construction is that the gap width easily and with accuracy by using washers with different Thickness can be changed. Preferably three pins are provided, which are equidistant around the central feed line are arranged.

The thermoplastic polymer is preferably a crystallizable polymer. Particularly suitable polymers are the polyolefins and copolymers thereof, particularly high and low density polyethylene and isotactic Polypropylene. However, the present method is also applicable to other thermoplastics such as e.g.

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to polyamides such as the nylons; Polyesters such as polyethylene terephthalate and polycarbonate; Vinyl polymers such as polyvinyl chloride, polystyrene, and poly (methyl methacrylate); and fluorinated polymers such as poly (tetrafluoroethylene), poly (monochlorotrifluoroethylene) and copolymers of tetrafluoroethylene and hexafluoropropylene. Homopolymers and, when appropriate, copolymers of such materials can be used in the present process.

It is essential that the liquid medium be a nonsolvent for the polymer at the temperature of the process so that the polymer and the liquid remain two separate phases throughout the process. to Suitable liquids include water and lower alcohols as well as hydrocarbons. It is clear, however, that the choice of the liquid medium is governed by the nature of the polymer and the operating temperature of the process. This is especially true for organic media such as hydrocarbons, which operate at higher temperatures can act as solvents for polymers. For this reason, the method according to the invention generally Water is preferred as the liquid medium. In some cases (when certain polyamides or polyesters are used) however, the preferred liquid medium is a hydrocarbon. It can be beneficial to be miscible with water Add compounds to the water to increase its viscosity,

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Change surface tension, density and / or its boiling point.

Although the polymer particles are preferably melted during the process, the process can be heat softened Particles are carried provided that they are pliable enough to be treated by treating the dispersion to be deformed according to the invention.

Since it is difficult to have a stable dispersion of molten polymers for long periods of time specially in To maintain aqueous media, the addition of a suitable stabilizing agent is generally desirable. Any suitable surfactant can be used in this context; a preferred one Stabilizing agent, however, especially when aqueous media are used, comprises a bifunctional polymer material, part of which is soluble in the liquid medium and part of which is insoluble. It is believed that such Materials stabilize the dispersion of molten particles in such a way that one in the liquid medium soluble coating is formed around the particles, which prevents or reduces the tendency that adjacent melted or heat-softened particles melt or agglomerate when they come into contact with one another. A An example of such a stabilizing material is a

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Copolymer of ethylene oxide and propylene oxide with a molecular weight of about 6OCO, suitable for use together with dispersions of polyolefins in aqueous media is suitable.

Stabilizers suitable for use in non-aqueous for example Hydrocarbon media suitable may comprise a polymeric backbone having side chains that can be solvated by the liquid medium and possibly other side chains that have an affinity for the material of the dispersed Particles have, in the event that the backbone itself does not have such an affinity. For example, polyethylene terephthalate (PET) dispersions can be used be stabilized in a hydrocarbon by a material, which is a backbone of a Copolymers of methyl methacrylate and glycidyl methacrylate and solvatable side chains of poly (12-hydroxystearic acid) having. In this case, the backbone itself has an affinity for the PET. On the other hand it can be a hydrocarbon dispersion of nylon are stabilized by a material that has a backbone of polymethyl methacrylate with side chains of poly (12-hydroxystearic acid) and also of poly (ethylene glycol) which has an affinity for nylon.

Another way of maintaining a stable dispersion of molten polymer particles is vigorously stirred mechanically. Of course you can too

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mechanically stirred and associated therewith a polymer or another suitable stabilizing agent or such Stabilizers are applied.

Dispersion of molten or heat-softened particles of certain polymers can also be achieved by dispersing solid particles of the polymer in the liquid medium produced without a stabilizing agent and the temperature the liquid can then be increased until the polymer particles melt or soften to the desired extent, immediately before the dispersion is sent to the fibrillator so that the particles have next to no opportunity to separate bal1 together.

It should be noted that the melted or heat-softened particles, once deformed into fibrils should be cooled as soon as possible to solidify them and if a molecular orientation was induced in the fibrils to ensure that at least some of it is retained. The temperature at which the liquid medium must be brought depends on the properties of the processed polymer. So the temperature of the liquid medium in general in the processing of the polymers mentioned below during the process in are in the following areas:

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Polymer temperature range

Polyethylene 14O-25O ° C

Polypropylene 170-280 ⁰ C

Polyvinyl chloride 100-2CO ⁰ C

Polystyrene 150-250 ⁰ C.

Polyamides 180-3CO ⁰ C

Polyester 200-35O ⁰ C

Operation at such temperatures often involves maintaining the liquid medium (e.g. Water) under increased pressure in order to avoid boiling phenomena, since it is essential that the medium is kept during the Deformation of the polymer particles remains in the liquid state. For example, prints can be up to 176 kg / cm or even can be applied even more.

The polymer particles should preferably have a diameter in the range from 0.1 μ to 1000 μm.

In a preferred embodiment of the method according to the invention, a slurry of polymer particles is used in a non-aqueous liquid medium in a stirred pressure vessel together with a suitable stabilizing agent brought and heated to a temperature above the melting point or softening point of the polymer. The dispersion thus formed is then poured into a a

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pressed suitable fibrillator, the body of which is kept at a temperature above the melting point of the polymer and driven through the gap-like opening of the fibrillator.

It should be noted that the method of the present invention can be smoothly combined with any other processes in which polymers arise in particulate or powdered form. Such processes can either Polymerizations in which polymers are formed in particulate form, or they can be a first Comprise stage in which polymer is formed in compact form,. then in a second stage of the process in the required particle shape is transferred.

Examples of the former polymerizations include emulsion polymerizations such as polystyrene and the polymerization of polyolefins using certain organometallic catalysts as liquids or Gas phase polymerization.

In the polymerization of olefins, preferred processes work with so-called organometallic catalysts Carriers (e.g. of the Ziegler type), which, however, are preferably

supported transition metal hydrocarbyl catalysts,

as described in the applicant's GB-PS 1,314,828

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are ("hydrccarbyl" = hydrocarbon radical).

For example, dry powdered polymers slurried with a suitable non-solvent and a stabilizer in a pressure vessel, to suitable Temperature and pressures brought and passed through a fibrillator to form fibrils, such as. described above, pressed or driven.

Alternatively, the polymer product can flow continuously from the polymerization vessel (usually in the form of a slurry stripped in a hydrocarbon diluent such as hexane), the diluent for example removed by "flash evaporation" and the resulting powdered product with a suitable non-solvent be slurried and sent directly to the pressure vessel * A mode of operation of this kind forms a continuous one Process for the production of polymer fibrils, starting from the monomer. It should be noted that it is not necessary all traces of the hydrocarbon diluent from the polymer prior to slurry with the nonsolvent to remove. For example, some of the hydrocarbon diluent can be used (say up to 1%) remain in the product during the fibril formation step.

To facilitate the cooling of the fibrils during

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The exit from the opening of the fibrillator is often its separation from the liquid non-solvent phase as quickly as possible preferred. This can be achieved, for example, that the emerging dispersion on a There is a grid or sieve with a suitable pitch or mesh size. In this way the bulk of the liquid phase separated from the fibrils that remain on the sieve. Since the liquid phase, however, during the fibrillation process is normally under increased pressure, it is useful to have a pressure relief when exiting the fibrillator, which facilitates rapid evaporation of the liquid phase. It is thus possible to use the electricity of fluid and fibrils from the fibrillator to direct into an expansion vessel so that the fluid rapidly evaporates and forms a mixture of fibrils and cooled liquid. Medium collects in the lower part of the expansion vessel. This is particularly useful when the Fixation or localization means for the gap-forming elements of the fibril] d: ors are contained within the opening, as this enables a completely free flow of the liquid and fibrils from the fibrillator directly into the expansion vessel. If, on the other hand, external fixation or Locating agents used occurs frequently clogging by fibrils and such often have to be arranged in a comparatively small expansion chamber which reduces the efficiency of the process.

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In the event that it is desired, the fibrils produced by the process according to the invention for production of non-woven sheet materials such as papers or the like, the above can be used Screen expediently comprise the Fourdrinier wires or screens of a papermaking machine. Alternatively the cooled slurry of fibrils in the liquid medium can be used to feed such a machine will. This is particularly useful when the non-solvent dispersant is water in papermaking processes usually work with water. The fibrils of the present method can be used alone or in Can be used in combination with other paper-making materials such as wood pulp.

The method according to the invention is illustrated below using the method explained by examples.

apparatus

The apparatus used in the following examples is indicated by the attached drawings; show it

Fig.l is a sectional view of an overall view of the apparatus; FIG. 2 shows a section through part of the apparatus of FIG on an enlarged scale;

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3 shows a modification of the apparatus part shown in FIG. 2;

4 shows a section through a modified form of the device according to Fig. 1 in detail;

FIG. 5 shows a section through part of the device from FIG FIG. 4 on an enlarged scale and FIG. 6 a plan view of the device according to FIG. In these drawings all similar parts have been given the same reference numbers.

According to Fig.l and 2 is a pressure vessel 1 with a stirrer an inlet 3 and an outlet 4, which is connected via a ball valve 6 and a feed line 7 to a fibrillator communicates. The pressure vessel 1 is also provided with electrical heating means (not shown). The fibrillator comprises a thick-walled pressure vessel 8 of generally cylindrical interior 9, the upper end of which is generally truncated like shape, the sloping sides of which consist of a series of ring steps 10 with increasing diameter, in which successive stages are connected by vertical annular surfaces 11. The solid inner element is generally frustoconical in shape with a stepped shape External surface that corresponds to that by the surfaces IO and limited part of the cavity 9 is complementary, but of smaller dimensions, so that a multi-stage annular gap 13 or such a gap-shaped opening through the

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Inner surfaces 10 and 11 of the cavity 9 and the step-shaped outer surface of the inner element 12 is formed. The inner element 12 is carried inside the cavity 9 by a rod lh which is provided with means (not shown) by which the element 12 can be raised or lowered within the cavity 9, varying the gap or opening between the upper ones Surfaces of the cavity 9 and the inner member 12. The pressure vessel is further provided with electrical heating means (not shown) and an outlet pipe 15 leading to a glass expansion vessel 16 which is provided at its upper end with a heat exchanger 17 which is provided with is connected to the vessel 16 via a baffle system 18. An outlet line 19 extends into the collecting container 20 or discharges material into it.

3 shows a modified form of the fibrillator 5, in which the upper surface of the cavity 9 in the pressure vessel 8 comprises a series of annular grooves 21 and ridges 22, the sides (of the grooves or ridges) form an angle of approximately 45 ° with the axis of the pressure vessel 8, with each other opposite sides of any particular degree enclose an angle of 90 °. With this modification the inner member 12 is in turn carried by a rod 14 within the cavity 9; its top or However, upper surface is with a series of annular

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Grooves and ridges are provided which are complementary to those of the upper surface of the cavity 9. The inner element 12 is from the upper surface of the cavity 9, delimiting a step-shaped gap 13 or such Opening removed.

FIG. 4 shows a modified form of the device according to FIG. 1, in which a fibrillator 5 of modified form is used, in which the support rod 14 is replaced by pegs which are located or fixed within a gap-like opening. As mentioned above, this form of fibrillator provides an unrestricted flow of the mixture of fibrils emerging from the opening 27 in liquid medium and enables them to be introduced directly into a large expansion vessel 23. The fibrillator used in this preferred embodiment, the one in enlarged form The scale shown in FIGS. A cylindrical inner member 26 is fitted in the cavity 25 to form a slit-shaped opening * 27 with a single step. The inner element 26 is spatially fixed by three pins 28 which pass through bores in the inner element 26 and into corresponding threaded holes

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provided bores in the outer element 24 are screwed. The inner element 26 is separated from the outer element 24 held away by circular washers 29 which fit around pegs 28 and between the interior Element 26 and the outer element 2 ^ · are clamped. The thickness of the washers 29 is determined according to the desired width of the horizontal part of the stepped opening 27 selected.

According to FIG. 4, the fibrillator shown in greater detail in FIGS. 5 and 6 is via a feed line connected to a ball valve, which in turn is provided with a (not shown in Figure 4) "stirred" or with a stirrer Vessel 1 is in communication, as shown in Fig.l. The expansion vessel 23 is equipped with a pressure-balancing "Vent" 30 and a circular lid provided with an opening 32 into which the fibrillator is fitted or inserted tightly. The upper edge of the vessel 23 fits together with the outer edge of the lid 31 and is sealed with a rubber ring seal 33.

General procedure

A suspension of the appropriate particulate Polymer was placed in container 1 and used to create a dispersion of molten polymer particles stirred and heated in the liquid medium used. Of the

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Container 1 was kept under nitrogen during the supply of heat, so that the contents, when the (desired) Temperature under increased (nitrogen / steam) pressure. The valve 6 was then opened for a certain period of time, so that the dispersion through the gap-like Opening 13 was driven into the cavity 9. Since the pressure decreases when passing through the opening 13, there is a rise in the cavity 9 a mixture of vapor and polymer fibrils is formed, which then via the outlet line 15 into the expansion chamber 16 passes where the steam condenses in the heat exchanger 17. The IS flapper system prevents fibrils from entering the Heat exchanger 17 arrive. A mixture of fibrils, liquid medium and stabilizer (if one is present is) is collected in the container 20.

It should be noted that the dispersion, if it is through a multi-stage (gap) opening 13, as shown in Fig.2 or Fig.3 is driven, flowing down through the central inlet pipe 7 and then in a series of radial paths is pressed outwards, with each path or each path a series of significant changes in direction has when "bypassing" the steps, as can be seen in Fig.2.

When using the device shown in Figures k to 6, the polymer dispersion in the feed pipe 7 is driven downwards and passes through the opening 27 of the fibrillator

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in a series of radial paths with a change in direction of 90 ° when passing the edge of the inner element 26 before exiting the opening 27 and it then passes directly into the container 23. A volume of cold water (equivalent to about 10 to 15 % of the container volume) is accommodated in the container 23 before the start of the process, which leads to a rapid cooling of the fibrils produced and aids in the condensation of the steam. When all of the polymer dispersion has passed through the fibrillator, the bulk of the produced fibrils is removed from the container as a "wet cake" which is either sent directly to standard papermaking equipment or dried to produce fibrils used for other applications can be.

example 1

200 g of an ethylene oxide-propylene oxide block copolymers ( "Pluronic P123", BASF Wyandotte Corporation) were dissolved in 2 I of deionized water. To this end, 100 g of polypropylene in powder form (ICI "Propathene HM 100") with a particle size of 100-400 μm and a melt index (MFI) of 6 were added. (All MFI measurements that are given here were carried out at 190 ^° C. with a load of 2.16 kg). This dispersion was transferred to the container 1 of an apparatus as shown in FIG. 4 and heated to 270.degree. The fibrillator was horizontal

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Gap of 2.2 mm and a vertical annular gap of 0.7 mm.

The pressure in the container 1 was brought to 63.2 kg / cm with nitrogen. The ball valve 6 was then opened for 10 seconds. At the end of the experiment, a three-dimensional fibrillar mass was removed from the expansion vessel. The diameters of the individual fibers were in the range from 1 to 20 μm. This mass was broken up and refined in a conventional treatment device for wood pulp and paper webs were produced both from the polypropylene fibrils alone and after mixing with wood pulp in amounts of 25, 50 and 75% by weight.

Example 2

A dispersion was prepared as in Example 1, except that 200 g of polypropylene powder were used. The dispersion was ^{heated to 254 °} C. and the pressure was brought to 57.6 kg / cm. The device used corresponded to FIG. 1, with the horizontal gap of the fibrillator being set to 0.4 mm and the vertical gap to 1 mm. The valve 6 was opened for 17 seconds and a mass of polypropylene fibril in the container 20 was collected.

Example 3

A 140 g copolymer of ethylene oxide and propylene oxide ("Pluronic 123" from BASF Wyandotte Corpn.) Stabilizer was deionized in 1500 ml

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Dissolved in water. Particles of polyethylene of density ho_her (75 g) having a melt index (MFI) of 50 (2.16 kg at 19O ⁰ C) and a particle size range of 50 to 150 pm. were then added to form a slurry, which was introduced into a pressure vessel 1 equipped with a stirrer. The dispersion was heated to 200 ° C. and the pressure increased to 38.7 kg / cm.

The V _e ntil 6 was then opened for 5 seconds and part of the dispersion is forced through the opening 13 of a fibrillator from that shown in Figure 2 type. The gap between the individual horizontal steps 10 and the corresponding horizontal surfaces of the inner member 12 was 150 µm.

The product collected in container 20 contained 34 grams of fibrillar polyethylene. A microscopic review of the solid product showed that it contained no undeformed polymer particles and that virtually everything was in shape of fibrils with diameters ranging from 1 to 15 µm and Aspect ratios of> 100 existed.

Example 4

A dispersion was prepared as in Example 1 except that 24 grams of polypropylene ( ¹¹ HM IOC ") and 24 grams of high density polyethylene having a 31 MFI were added.

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The dispersion was ^{heated to 270 °} C. and brought to a pressure of 69 kg / cm. The device and outlet or gap widths corresponded to those used in Example 1.

The valve 6 was opened for 10 seconds and a fibrillar mass was recovered from the expansion vessel.

This was broken up to produce fibrils with lengths of 1 to 10 mm, which were used to make a mat of fibrillar material. This mat was then ^{heated to 130 °} C. and lightly pressed. A cloth-like material was formed by this treatment.

Example 5

A dispersion was prepared as in Example 1 except that 45 grams of polypropylene ("HM 100") and 5 grams of low density polyethylene were used. The dispersion was ^{heated to 270 °} C. and brought to a pressure of 63.2 kg / cm and fibrillated as described in Example 4 »

The product was crushed mm for the generation of fibrils having lengths of 1 to 10, which were formed into a mat, which was heated to 120 ⁰ C and lightly pressed to form a cloth-like material.

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Example 6

A dispersion was prepared as in Example 1, except that 48 g of polypropylene granules with an MFI of 6 and an average particle size of 3 mm were used. This was ^{heated to 270 °} C. at a pressure of 68.2 kg / cm and fibrillated as described in Example 4. The valve 6 was opened for 10 seconds and a fibrillary mass was obtained from the expansion vessel, the fibrils of which had diameters in the range from 1 to 100 μm .

The fibrils were disrupted and refined using standard processing equipment Wood pulp and paper-like sheet materials were made.

Example 7

A dispersion was prepared as in Example 1, except that 50 g of a polyethylene-vinyl acetate copolymer (I.C.I. "Alkathene 14246") with an MFI of 33 and a density of 0.937 were used. The mean particle size was 300 ^ m.

The dispersion was fibrillated described at 250 ⁰ C at a pressure of 69 kg / cm, and heated as in Βείεφϊθΐ 4, wherein the valve (6) 14 seconds has been opened long. The fibril diameters ranged from 1 to 50 µm and

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the fibril lengths in the range from 1 to 10 mm.

Example 8

An ethylene oxide-propylene oxide block copolymer (150 g) ("Pluronic F127" from BASF Wyandotte) was deionized in 1.5 l Dissolved in water. 75 g PVC / vinyl acetate copolymer powder (I.C.I. "Corvic R46 / 88") were added to this.

^{The dispersion was heated to 20O 0} C at a pressure of 40.1 kg / cm and fibrillated as described in Example 2, the horizontal gap being set to 0.15 mm. The V _e ntil was opened for 15 seconds and a fibrillar mass collected from the expansion tank.

Example 9

A dispersion was mixed with 2 1 of aliphatic hydrocarbon having a boiling range of 220-250 ⁰ C, 100 g of polyethylene terephthalate, "Terylene", having a particle size 1-25 μπι ^unc * 6 g of a "comb" -Stabilisators prepared. This stabilizer was of the type described in Example 21 of DT-OS 2,215,732 and had side chains of poly (1,2-hydroxy stearic acid) with an M of 2000 on a backbone of methyl methacrylate / glycidyl methacrylate copolymers with an M of 15,000.

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^{This dispersion was heated to 280 °} C. under a pressure of 42.2 kg / cm and fibrillated as described in Example 1, the horizontal gap being 0.5 mm and the vertical gap 0.7 mm wide. The valve 6 was opened for 25 seconds and a mass of fine fibrils was collected from the expansion vessel. These fibrils were dried and a portion made into nonwoven mats. Some of the fibrils were also twisted into yarn for fabric manufacture.

Example IC

A dispersion was prepared with 2 liters of aliphatic hydrocarbon with a boiling range of 160 to 18 ° C., 100 g of nylon-6,6 with a particle size range of 1 to 25 μm and 6 g of a "double-comb" stabilizer. This stabilizer was of the type described in Example 2 of DT-OS 2,429 and comprised side chains of (a) poly (1,2-hydroxystearic acid) of M 1500 and (b) methoxypolyethylene glycol of M 750 on a folymethyl methacrylate backbone.

This dispersion was ^{heated to 250 °} C. under a pressure of 56.2 kg / cm. It was fibrillated with an apparatus and gap settings as in Example 9. The valve was opened for 25 seconds and a mass of fine fibrils was collected. These fibrils were dried and

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some processed into non-woven mats. Others have been twisted into yarns for fabric manufacture.

It should be noted that the stabilizers ,, used in the above procedures were used from the fibrillar fat. product can be smoothly recovered and reused. This is most expediently done by recycling the die Liquid medium containing stabilizers.

As mentioned above, the method can be used, in particular when using the essentially shown in FIG Apparatus can be adapted smoothly to continuous operation. For example, the dispersion in vessel 1 made with stirring device at the beginning and then by pumping through one between the valve 6 and the Container 1 arranged heat exchanger are heated. The fibrils and the liquid medium can then be continuous removed from the expansion tank 23 and the fibrils separated from the liquid medium, for example by filtration while the liquid medium is returned to the container 1.

It should also be noted that when using water as the liquid medium, small amounts of the stabilizer with the fibrils can be united. That has the benefit of making them hydrophilic, which is of great use when they are to be used for paper production by traditional methods using water.

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Claims (1)

Claims Λ Method of making fibrils of a thermoplastic Folymeren, in which a dispersion of melted or heat softened particles of the polymer in a liquid medium that is a non-solvent for the polymer under the prevailing conditions, by a Opening is driven through, according to patent ... (German patent application P 23 48 485.7), characterized in that that the dispersion by means of an elongated slot or gap-like opening of corresponding Geometry is forced to at least one substantial change in direction when it passes through it. 2. The method according to claim 1, characterized in that the dispersion leads to a change in direction of about is forced. 3. The method according to claim 1 or 2, characterized in that the dispersion is suitable for stabilization surfactant is added, which preferably comprises a bifunctional polymeric material, part of which is soluble in the liquid medium and part of which is insoluble. 50 9 8 39/0869 A. The method according to any one of the preceding claims, characterized in that the polymer dispersion under Use of polyolefin or of olefin copolymers and in particular starting from polypropylene. 5. The method according to claim 4, characterized in that that water is used as the liquid medium. 6. Apparatus for performing the method according to claim 1, characterized by a pair of rigid elements (8,12) each having a flat surface (10 and top of 12) facing each other at a distance delimiting a gap-like opening (13), one of these elements (8 or 12) having a feed line (7) provided ijst with a mouth in the flat surface and the supply of polymer dispersion to the central area of the gap-shaped Opening (13) allows and these surfaces (10 or top of 12) are provided with means on the periphery are causing the dispersion to undergo a substantial change in direction before exiting the gap-like force opening. 7. Apparatus according to claim 6, characterized in that the gap-delimiting surfaces are the flat end faces 509839/0869 of two complementary generally cylindrical solid elements, one spanning and one engaging Include element, wherein the engaging element (12) disposed vertically within the overlapping element (8) and is removed therefrom to form a gap-like opening (13) in the form of an annular step gap, the Feed line (7) is connected to a central opening in the base of the overlapping element (8). 8. Apparatus according to claim 7, characterized in that the outer surface of the engaging element (12) and the inner surface of the spanning element (8) are tapered in a series of discrete complementary steps of increasing and decreasing radius, respectively, the Steps (10) are connected to one another by corresponding vertical annular surfaces (11) (FIG. 2). 9. Apparatus according to claim 7 or 8, characterized in that that the two fixed or rigid elements (24,26) relative to one another by two or more fixing pins (28) be fixed, which through holes in the one element (26) reach through and screw into threaded holes in the other element with the tenons through the flat end faces of the elements pass through and are provided with washers (29) which have a thickness that is equal to the desired thickness of the gap (27) created by the washers clamped between the two elements 509839/0869 is defined. 10. Device according to one of claims 6 to 9 »characterized in that the gap-shaped outlet opening (13) is formed by two opposing elements (8 and 12) with complementary annular grooves or ridges (21,22) are provided (Fig. 3). 11. The device according to claim 9 »characterized in that the fibrillator (5) fitted into an expansion chamber (23) is. 12. Use of the fibrils produced according to claim 1 for the production of web materials, in particular non-woven fabrics. 509839/0869 3S Blank page